Estimation of dicarbonyl compounds intake in Italy and their potential role against food spoilage/pathogenic bacteria

Foods, from the earliest times, are subjected to man-made modifications to ensure microbiological safety, enzymatic inactivation, destruction of toxic substances, and optimization of storage time. An undisputable role in making the food softer, tasty and preservable over time is exerted by heat treatment. It is during this phase that a series of chain reactions, known like Maillard's reaction, are triggered. During this reaction, products that affect the flavor, color and aroma of foods are formed. Among these, glyoxal, methylglyoxal and 3-deoxyglucosone are of particular importance. These compounds are present in food, have antimicrobial activity, are promoters of advanced glycation end products formationand also have toxic effects in in vitro and in vivo studies. Research activity carried out during Ph.D. study had a common thread: increasing knowledge on 1,2-dicarbonyl compounds. In this field, the overall aims of this thesis work were: assessment of the content of dicarbonyl compounds in Italian food; assessment of their dietary intake; study of formation/degradation of dicarbonyl compounds using food model systems; evaluation of antimicrobial activity of the main dicarbonyl compounds; study of the interaction between the dicarbonyl compounds and the nutrients present in the microbiological culture media, both in the presence and absence of the microorganism. The results obtained by the survey on Italian food show that the concentration is variable and the predominant 1,2-dicarbonyl compounds is 3-deoxyglucosone. The estimation on dietary intake with a Total Diet Study-like investigation, have brought new evidence to assert that the ingestion with foods is high especially for infants (0-2 years) and children (3-9 years). The results obtained with the model systems show that time, temperature and ingredients have a strong influence on the formation of the compounds and that it is possible to reduce the level of 1,2-dicarbonyl compounds. The results of antimicrobial assays lead us to conclude that dicarbonyl compounds, especially GO and MGO, could have a role in the microbial stability of foods, although food composition may strongly influence their availability to act as antimicrobials. The results obtained by the study of the interaction between the dicarbonyl compounds and the nutrients present in the culture media allow us to assert that the 1,2-dicarbonyl compounds are degraded very quickly when they come into contact with bacteria. The results obtained outline a framework of knowledge that is a prelude to subsequent important developments.